Superior VD1824NM Installation And Operation Instructions Manual page 7

standard method defi nes a confi ned space as
a space whose volume is less than 50 cubic
feet per 1,000 Btu per hour (4.8 m
of the aggregate input rating of all appliances
installed in that space and an unconfi ned
space as a space whose volume is not less
than 50 cubic feet per 1,000 Btu per hour (4.8
3
m per kw) of the aggregate input rating of
all appliances installed in that space. Rooms
communicating directly with the space in
which the appliances are installed*, through
openings not furnished with doors, are consid-
ered a part of the unconfi ned space.
Where the air infi ltration rate of a structure is
known, the Known Air Infi ltration Rate Method
may be used. Follow The National Fuel Gas
Code, ANSI Z223.1/NFPA 54 to use this
method to determine if the space is confi ned
or unconfi ned.
* Adjoining rooms are communicating only if
there are doorless passageways or ventilation
grills between them.
DETERMINING FRESH-AIR FLOW
FOR FIREPLACE LOCATION
Determining if You Have a Confi ned or
Unconfi ned Space Using the Standard
Method
Use this work sheet to determine if you have
a confi ned or unconfi ned space.
Space: Includes the room in which you will
install fi replace plus any adjoining rooms with
doorless passageways or ventilation grills
between the rooms.
1. Determine the volume of the space (length
x width x height).
Length x Width x Height =__________cu. ft.
(volume of space)
Example: Space size 20 ft. (length) x 16 ft.
(width) x 8 ft. (ceiling height) = 2,560 cu. ft.
(volume of space)
If additional ventilation to adjoining room
is supplied with grills or openings, add the
volume of these rooms to the total volume
of the space.
2. Multiply the space volume by 20 to determine
the maximum Btu/Hr the space can support.
________ (volume of space) x 20 = (Maxi-
mum Btu/Hr the space can support)
Example: 2,560 cu. ft. (volume of space) x
20 = 51,200 (maximum Btu/Hr the space can
support)
3. Add the Btu/Hr of all fuel-burning appliances
in the space.
126838-01C
Vent-free fi replace
Gas water heater*
3
per kw)
Gas furnace
Vented gas heater
Gas fi replace logs
Other gas appliances* + __________ Btu/Hr
Total
* Do not include direct-vent gas appliances.
Direct-vent draws combustion air from the
outdoors and vents to the outdoors.
Example:
Gas water heater
Vent-free fi replace
Total
4. Compare the maximum Btu/Hr the space
can support with the actual amount of Btu/
Hr used.
_______ Btu/Hr (maximum the space can
support)
_______ Btu/Hr (actual amount of Btu/Hr
used)
Example: 51,200 Btu/Hr (maximum the
The space in the example is a confi ned space
because the actual Btu/Hr used is more than the
maximum Btu/Hr the space can support. You
must provide additional fresh air. Your options
are as follows:
A. Rework worksheet, adding the space of an
adjoining room. If the extra space provides an
unconfi ned space, remove door to adjoining
room or add ventilation grills between rooms.
See Ventilation Air From Inside Building.
B. Vent room directly to the outdoors. See
Ventilation Air From Outdoors, Page 8.
C. Install a lower Btu/Hr heater, if lower Btu/Hr
size makes room unconfi ned.
If the actual Btu/Hr used is less than the maxi-
mum Btu/Hr the space can support, the space is
an unconfi ned space. You will need no additional
fresh air ventilation.
WARNING: If the area in which
the heater may be operated does
not meet the required volume for
indoor combustion air, combustion
and ventilation air shall be provided
by one of the methods described in
the National Fuel Gas Code, ANSI
Z223.1/NFPA 54, the International
Fuel Gas Code, or applicable local
codes.
SuperiorFireplaces.US.com
__________ Btu/Hr
__________ Btu/Hr
__________ Btu/Hr
__________ Btu/Hr
__________ Btu/Hr
= __________ Btu/Hr
40,000
__________ Btu/Hr
31,500
+ __________ Btu/Hr
71,500
= __________ Btu/Hr
space can support)
71,500 Btu/Hr (actual amount of
Btu/Hr used)
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